<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        div{color: red }
        /*important是将优先级提升到最高*/
        p{color: green !important;}
        #p1{color: blue}
    </style>
</head>
<body>
<div>
  div
  <p id="p1">这是p标签</p>
  <span>这是span</span>
  <a href="">超链接</a>
</div>
</body>
</html>